Perhaps you should try some spelling variations:
"tres estudios peruanos." » "tres estudios urbanos.", "tres estudios americanos.", "tres estudios ensayos.", "otros estudios peruanos.", "los estudios peruanos.", "dos estudios peruanos."
"seis estudioss urbano." » "seis estudios urbanos.", "seis estudio urbano.", "seis estudios urbano.", "mis estudios urbano.", "seire estudios urbano."
"series estudios urbano." » "serie estudios urbano.", "seis estudios urbano.", "leyes estudios urbano.", "series estudios urbanos.", "series estudio urbano.", "series estudios hispano."

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("seis estudioss urbano.") or ("series estudios urbano."))) or ("tres estudios peruanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("seis estudioss urbano.") OR ("series estudios urbano."))) OR ("tres estudios peruanos.")).
• Removing quotes may allow a broader search: (((( seis estudioss urbano. ) or ( series estudios urbano. ))) or ( tres estudios peruanos. )).
• Adding a wildcard symbol may retrieve word variants: (((("seis estudioss urbano.") or ("series estudios urbano."))) or ("tres estudios peruanos."))*.